JP2013147688A - Surface-treated copper foil for use in copper-clad laminated board, and copper-clad laminated board employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-treated copper foil for use in a copper-clad laminated board, suitably adhering to a resin, with the resin excellent in transparency after removing the copper foil by etching.SOLUTION: A surface-treated copper foil for use in a copper-clad laminated board includes roughened particles formed on the surface of the copper foil by a roughening treatment, with a mean roughness Rz of the roughened surface being 0.5 to 1.3 μm, gloss of the roughened surface being 0.5 to 68, and a ratio A/B of a surface area A of the roughened particles relative to an area B obtained upon viewing the roughened particles in a plan view from the surface side of the copper foil, being 2.00 to 2.45.

Description

  The present invention relates to a surface-treated copper foil for a copper-clad laminate and a copper-clad laminate using the same, and in particular, a copper-clad laminate suitable for a field where transparency of the remaining resin after etching the copper foil is required. The present invention relates to a surface-treated copper foil for plates and a copper-clad laminate using the same.

  In a small electronic device such as a smartphone or a tablet PC, a flexible printed wiring board (hereinafter referred to as FPC) is adopted because of easy wiring and light weight. In recent years, with the enhancement of functions of these electronic devices, the signal transmission speed has been increased, and impedance matching has become an important factor in FPC. As a measure for impedance matching with respect to an increase in signal capacity, a resin insulation layer (for example, polyimide) serving as a base of an FPC has been increased in thickness. On the other hand, the FPC is processed such as bonding to a liquid crystal substrate and mounting of an IC chip. The alignment at this time is visible through the resin insulation layer remaining after etching the copper foil of the copper clad laminate. Therefore, the visibility of the resin insulating layer is important.

Moreover, a copper clad laminated board can also be manufactured even if it uses the rolled copper foil by which the roughening plating was given to the surface. This rolled copper foil usually uses tough pitch copper (oxygen content of 100 to 500 ppm by weight) or oxygen-free copper (oxygen content of 10 ppm by weight or less) as a raw material, and after hot rolling these ingots, It is manufactured by repeating cold rolling and annealing to a thickness. Patent Document 1 proposes to use a low-roughness electrolytic foil having a high surface glossiness as a conductor layer.
On the other hand, Patent Document 2 proposes a rolled copper foil having an oil pit depth of 2.0 μm or less on the surface formed by a cold rolling process under conditions such as oil film control as a copper foil having excellent flexibility. ing.

JP 2004-98659 A JP 2001-58203 A

In Patent Document 1, a low-roughness copper foil obtained by improving adhesion with an organic treatment agent after blackening treatment or plating treatment is broken due to fatigue in applications where flexibility is required for a copper-clad laminate. May be inferior in resin transparency. Further, even if a rolled copper foil having an oil pit state as described in Patent Document 2 is used, sufficient transparency of the resin cannot be obtained. Thus, in the prior art, the resin transparency after removing the rolled copper foil by etching was low, and the chip alignment could not be performed smoothly.
The present invention provides a copper foil for a copper-clad laminate, which adheres well to a resin and is excellent in resin transparency after the copper foil is removed by etching.

  As a result of intensive studies, the present inventors have found that the surface average roughness Rz of the copper foil bonded to the resin substrate affects the resin transparency after the copper foil is removed by etching. . That is, it has been found that as the surface average roughness Rz on the side of the copper foil bonded to the resin substrate is larger, the resin transparency after the copper foil is removed by etching becomes poorer.

  In one aspect of the present invention completed based on the above knowledge, roughened particles are formed on the surface of the copper foil by the roughening treatment, and the average roughness Rz of the roughened treatment surface is 0.5 to 1.3 μm. The ratio A between the surface roughness A of the roughened particles and the area B obtained when the roughened particles are viewed in plan from the copper foil surface side. It is the surface-treated copper foil for copper clad laminated boards whose / B is 2.00-2.45.

  In one embodiment of the surface-treated copper foil for copper-clad laminate according to the present invention, the average roughness Rz is 0.5 to 1.1 μm.

  In another embodiment of the surface-treated copper foil for a copper clad laminate according to the present invention, the average roughness Rz is 0.6 to 0.9 μm.

  In still another embodiment of the surface-treated copper foil for a copper clad laminate according to the present invention, the glossiness is 1.0 to 40.

  In still another embodiment of the surface-treated copper foil for a copper-clad laminate according to the present invention, the glossiness is 4.8 to 35.

  In still another embodiment of the surface-treated copper foil for copper-clad laminate according to the present invention, the A / B is 2.00 to 2.30.

  In still another embodiment of the surface-treated copper foil for copper-clad laminate according to the present invention, the A / B is 2.00 to 2.15.

  When the copper foil is bonded to both surfaces of a 50 μm thick resin substrate from the surface of the roughened surface and then removed by etching, the light transmittance of the resin substrate becomes 30% or more.

  In another aspect, the present invention is a copper clad laminate configured by laminating the surface-treated copper foil and a resin substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the surface treatment copper foil for copper clad laminated boards excellent in transparency of resin after adhere | attaching resin favorably and removing the copper foil by etching can be provided.

It is the observation photograph of the printed matter of (a) Comparative example 1, (b) Example 1, (c) Example 2, (d) Example 7, and (e) Example 3 in the case of visibility evaluation. It is a SEM observation photograph of the copper foil surface of (a) Comparative Example 1, (b) Example 1, (c) Example 2, (d) Example 7, and (e) Example 3 in the Rz evaluation. .

[Form and manufacturing method of surface-treated copper foil]
The copper foil used in the present invention may be either an electrolytic copper foil or a rolled copper foil. Usually, the surface of the copper foil that adheres to the resin base material, that is, the roughened surface, has a fist-like shape on the surface of the copper foil after degreasing in order to improve the peel strength of the copper foil after lamination. A roughening process for electrodeposition is performed. Although the electrolytic copper foil has irregularities at the time of manufacture, the irregularities are further increased by enhancing the convex portions of the electrolytic copper foil by roughening treatment. In the present invention, this roughening treatment can be performed by copper-cobalt-nickel alloy plating. Ordinary copper plating or the like may be performed as a pretreatment before roughening, and ordinary copper plating or the like may be performed as a finishing treatment after roughening in order to prevent electrodeposits from dropping off. The content of treatment may be somewhat different between the rolled copper foil and the electrolytic copper foil. In the present invention, including such pretreatment and finishing treatment, known treatments related to copper foil roughening are included as necessary, and are collectively referred to as roughening treatment.

Copper as the roughening treatment in the present invention - cobalt - nickel alloy plating, by electrolytic plating, deposition amount of 15~40mg / dm ² of copper -100~3000μg / dm ² of cobalt -100~900μg / dm ² of nickel The ternary alloy layer can be formed as follows. If the amount of deposited Co is less than 100 μg / dm ² , the heat resistance may deteriorate and the etching property may deteriorate. When the amount of Co deposition exceeds 3000 μg / dm ² , it is not preferable when the influence of magnetism must be taken into account, etching spots may occur, and acid resistance and chemical resistance may deteriorate. If the Ni adhesion amount is less than 100 μg / dm ² , the heat resistance may deteriorate. On the other hand, when the Ni adhesion amount exceeds 900 μg / dm ² , the etching residue increases. Preferred Co deposition amount is 1000~2000μg / dm ^2, preferably nickel coating weight is 200~400μg / dm ^2. Here, the etching stain means that Co remains without being dissolved when etched with copper chloride, and the etching residue means that Ni remains without being dissolved when alkaline etching is performed with ammonium chloride. It means that.

An example of a general bath and plating conditions for forming such a ternary copper-cobalt-nickel alloy plating is as follows:
Plating bath composition: Cu 10-20 g / L, Co 1-10 g / L, Ni 1-10 g / L
pH: 1-4
Temperature: 40-50 ° C
Current density D _k : 20 to 30 A / dm ²
Plating time: 1-5 seconds

After the roughening treatment, a cobalt-nickel alloy plating layer of nickel having an adhesion amount of 200 to 3000 μg / dm ² and cobalt-100 to 700 μg / dm ² can be formed on the roughened surface. This treatment can be regarded as a kind of rust prevention treatment in a broad sense. This cobalt-nickel alloy plating layer needs to be performed to such an extent that the adhesive strength between the copper foil and the substrate is not substantially reduced. If the amount of cobalt adhesion is less than 200 μg / dm ² , the heat-resistant peel strength is lowered, and the oxidation resistance and chemical resistance may be deteriorated. As another reason, if the amount of cobalt is small, the treated surface becomes reddish, which is not preferable. When the amount of cobalt deposition exceeds 3000 μg / dm ² , it is not preferable when the influence of magnetism must be taken into account, etching spots occur, and deterioration of acid resistance and chemical resistance is considered. A preferable cobalt adhesion amount is 500 to 3000 μg / dm ² . On the other hand, if the nickel adhesion amount is less than 100 μg / dm ² , the heat-resistant peel strength is lowered and the oxidation resistance and chemical resistance are deteriorated. When nickel exceeds 700 μg / dm ² , the alkali etching property is deteriorated. A preferable nickel adhesion amount is 200 to 600 μg / dm ² .

An example of the conditions for cobalt-nickel alloy plating is as follows:
Plating bath composition: Co 1-20 g / L, Ni 1-20 g / L
pH: 1.5-3.5
Temperature: 30-80 ° C
Current density D _k : 1.0 to 20.0 A / dm ²
Plating time: 0.5-4 seconds

According to the present invention, a zinc plating layer having an adhesion amount of 10 to 80 μg / dm ² is further formed on the cobalt-nickel alloy plating. If the zinc adhesion amount is less than 10 μg / dm ² , the heat deterioration rate improving effect may be lost. On the other hand, when the zinc adhesion amount exceeds 80 μg / dm ² , the hydrochloric acid resistance deterioration rate may be extremely deteriorated. Preferably, the zinc adhesion amount is 20 to 60 μg / dm ² , more preferably 30 to 50 μg / dm ² .

An example of the galvanizing conditions is as follows:
Plating bath composition: Zn 100 to 300 g / L
pH: 3-4
Temperature: 50-60 ° C
Current density D _k : 0.1 to 0.5 A / dm ²
Plating time: 1-3 seconds

  A zinc alloy plating layer such as zinc-nickel alloy plating may be formed instead of the zinc plating layer, and a rust prevention layer may be formed on the outermost surface by chromate treatment or application of a silane coupling agent. Good.

Moreover, the surface-treated copper foil of the present invention is a ternary composed of copper, cobalt, and nickel on the primary particle layer after forming a primary particle layer of copper on the surface of the copper foil in advance as a roughening treatment. You may form the secondary particle layer which consists of a system alloy. In this case, an example of plating conditions for the primary particles of copper is as follows:
Plating bath composition: Cu 10-25 g / L, sulfuric acid 50-100 g / L
Temperature: 25-50 ° C
Current density D _k : 10 to 70 A / dm ²
Plating time: 5 to 25 seconds Coulomb amount 50 to 500 As / dm ²

An example of secondary particle plating conditions is as follows:
Plating bath composition: Cu 10-20 g / L, nickel 5-15 g / L, cobalt 5-15 g / L
pH: 2-3
Temperature: 30-50 ° C
Current density D _k : 20 to 60 A / dm ²
Plating time: 1 to 5 seconds Coulomb amount 30 to 70 As / dm ²

[Surface roughness Rz]
In the surface-treated copper foil of the present invention, roughened particles are formed on the surface of the copper foil by a roughening treatment, and the average roughness Rz of the roughened surface is 0.5 to 1.3 μm. With such a configuration, the peel strength is increased and the resin is satisfactorily adhered to the resin, and the light transmittance of the resin after the copper foil is removed by etching is improved. As a result, it is easy to perform alignment and the like when mounting an IC chip through a positioning pattern that is visible through the resin. When the average roughness Rz is less than 0.5 μm, the copper foil surface is not sufficiently roughened and cannot be sufficiently bonded to the resin. On the other hand, if the average roughness Rz is more than 1.3 μm, the unevenness of the resin surface after the copper foil is removed by etching becomes large, and as a result, the light transmittance of the resin becomes poor. The average roughness Rz of the roughened surface is preferably 0.5 to 1.1 μm, and more preferably 0.6 to 0.9 μm.

(Light transmittance)
Since the average roughness Rz of the roughened surface is controlled as described above, the surface-treated copper foil of the present invention has a light transmittance of the resin substrate in a portion where the copper foil is removed after being bonded to the resin substrate. Becomes better. Specifically, when the surface-treated copper foil of the present invention is bonded to both surfaces of a 50 μm thick resin substrate from the surface of the roughened surface, the light transmittance of the resin substrate is removed when the copper foil is removed by etching. May be 30% or more, preferably 50% or more.

[Glossiness]
The glossiness of the roughened surface of the surface-treated copper foil greatly affects the light transmittance of the above resin. That is, the higher the glossiness of the roughened surface, the better the transmittance of the resin described above. For this reason, the glossiness of the roughened surface of the surface-treated copper foil of the present invention is 0.5 to 68, preferably 1.0 to 40, and more preferably 4.8 to 35.

[Particle surface area]
The ratio A / B between the surface area A of the roughened particles and the area B obtained when the roughened particles are viewed in plan from the copper foil surface side greatly affects the light transmittance of the resin. That is, if the surface roughness Rz is the same, the smaller the ratio A / B, the better the transmittance of the resin described above. For this reason, the surface-treated copper foil of the present invention has a ratio A / B of 2.00 to 2.45, preferably 2.00 to 2.30, and preferably 2.00 to 2.15. Is more preferable.

  By controlling the current density and the plating time during particle formation, the particle morphology and formation density are determined, and the surface roughness Rz, glossiness, and particle area ratio A / B can be controlled.

  The surface-treated copper foil of the present invention can be bonded to a resin substrate from the roughened surface side to produce a copper-clad laminate. The resin substrate is not particularly limited as long as it has characteristics applicable to a printed wiring board or the like. For example, a paper base phenol resin, a paper base epoxy resin, a synthetic fiber cloth base epoxy resin for rigid PWB Glass cloth / paper composite base material epoxy resin, glass cloth / glass nonwoven fabric composite base material epoxy resin, glass cloth base material epoxy resin, etc. can be used, and polyester film, polyimide film, etc. can be used for FPC.

  In the case of the rigid PWB, a prepreg is prepared by impregnating a base material such as a glass cloth with a resin and curing the resin to a semi-cured state. It can be carried out by superposing a copper foil on the prepreg from the opposite surface of the coating layer and heating and pressing.

  The copper-clad laminate of the present invention can be used for various printed wiring boards (PWB) and is not particularly limited. For example, from the viewpoint of the number of layers of the conductor pattern, single-sided PWB, double-sided PWB, and multilayer PWB It can be applied to (three or more layers), and can be applied to rigid PWB, flexible PWB (FPC), and rigid flex PWB from the viewpoint of the type of insulating substrate material.

  Copper foil was prepared as Examples 1-15 and Comparative Examples 1-8, and the plating process was performed on the conditions of Tables 1-4 as a roughening process on one surface. Here, as copper foils of Examples 1 to 12 and Comparative Examples 2 to 6 and 8, rolled copper foil of tough pitch copper (JIS H3100 C1100R) manufactured by JX Nippon Mining & Metals was used. Moreover, as copper foil of Examples 13-15 and Comparative Examples 1 and 7, the electrolytic copper foil HLPLC foil by JX Nippon Mining & Metals was used.

Various evaluation was performed as follows about each sample of the Example and comparative example which were produced as mentioned above.
(1) Measurement of surface roughness (Rz);
Using a contact roughness meter SP-11 manufactured by Kosaka Laboratories, ten-point average roughness was measured for the roughened surface in accordance with JIS B0601-1994. The measurement position was changed 10 times in parallel with the rolling direction under the conditions of a measurement standard length of 0.8 mm, an evaluation length of 4 mm, a cut-off value of 0.8 mm, and a feed rate of 0.1 mm / sec. The value of was obtained.

(2) Particle area ratio (A / B);
The surface area of the roughened particles was measured by a laser microscope. Using a laser microscope VK8500 manufactured by Keyence Corporation, the three-dimensional surface area A in an area equivalent to 100 × 100 μm of the roughened surface (992.44.4 μm ^{2 in} actual data) is measured, and the three-dimensional surface area A ÷ two-dimensional surface area B = Setting was performed by a method of obtaining an area ratio (A / B).

(3) Glossiness;
A roughened surface was measured at an incident angle of 60 degrees perpendicular to the rolling direction using a gloss meter PG-1 manufactured by Nippon Denshoku Co., Ltd. in accordance with JIS Z8741.

(4) Light transmittance;
The copper foil was bonded to both surfaces of a polyimide film with a thermosetting adhesive for lamination (thickness 50 μm), and the copper foil was removed by etching (ferric chloride aqueous solution) to prepare a sample film. With respect to the obtained resin layer, the light transmittance was measured using a spectrophotometer V-660 manufactured by JASCO Corporation with a slit of 10 mm and a wavelength of 620 nm.

(5) Visibility (resin transparency);
The copper foil was bonded to both surfaces of a polyimide film with a thermosetting adhesive for lamination (thickness 50 μm), and the copper foil was removed by etching (ferric chloride aqueous solution) to prepare a sample film. The printed material was attached to one surface of the obtained resin layer, and the visibility of the printed material was judged from the opposite surface through the resin layer. The printed product with a clear outline was evaluated as “◯” (passed), and the printed outline was evaluated as “x” (failed).

(6) Peel strength (adhesive strength);
In accordance with PC-TM-650, the normal peel strength was measured with a tensile tester Autograph 100, and the normal peel strength of 0.7 N / mm or more could be used for copper-clad laminate applications.
Table 5 shows the conditions and evaluation of each test.

(Evaluation results)
Examples 1 to 15 all had good transmittance, visibility, and peel strength.
In Comparative Examples 1, 2, and 5, since the average roughness Rz of the roughened surface was more than 1.3 μm, the transmittance was poor.
Since the comparative example 3 had a glossiness of more than 68, the peel strength was poor.
In Comparative Example 4, since the area ratio A / B was less than 2.00, the peel strength was poor.
In Comparative Example 6, since the average roughness Rz of the roughened surface was less than 0.5 μm, the peel strength was poor.
Since the comparative example 7 had a glossiness of less than 0.5, the transmittance was poor.
In Comparative Example 8, since the area ratio A / B was more than 2.45, the transmittance was poor.
FIG. 1 shows the printed matter of (a) Comparative Example 1, (b) Example 1, (c) Example 2, (d) Example 7, and (e) Example 3 in the above-described visibility evaluation. Each photo is shown.
FIG. 2 shows (a) Comparative Example 1, (b) Example 1, (c) Example 2, (d) Example 7, and (e) Example 3 of the copper foil surface in the above Rz evaluation. SEM observation photographs are shown respectively.

Claims (9)

Roughening particles are formed on the surface of the copper foil by roughening treatment, the average roughness Rz of the roughening treatment surface is 0.5 to 1.3 μm, and the glossiness of the roughening treatment surface is 0.5 to 68. ,
For a copper clad laminate in which the ratio A / B between the surface area A of the roughened particles and the area B obtained when the roughened particles are viewed in plan from the copper foil surface side is 2.00 to 2.45. Surface treated copper foil.   The surface-treated copper foil for copper clad laminates according to claim 1, wherein the average roughness Rz is 0.5 to 1.1 µm.   The surface-treated copper foil for copper-clad laminate according to claim 2, wherein the average roughness Rz is 0.6 to 0.9 µm.   The surface-treated copper foil for a copper-clad laminate according to any one of claims 1 to 3, wherein the glossiness is 1.0 to 40.   The surface-treated copper foil for a copper-clad laminate according to claim 4, wherein the glossiness is 4.8 to 35.   Said A / B is 2.00-2.30, The surface-treated copper foil for copper clad laminated boards in any one of Claims 1-5.   The surface-treated copper foil for a copper clad laminate according to claim 6, wherein the A / B is 2.00 to 2.15.   The light transmittance of the resin substrate becomes 30% or more when the copper foil is removed by etching after bonding the copper foil to both surfaces of a 50 μm thick resin substrate from the surface of the roughening treatment. The surface-treated copper foil for copper clad laminated boards in any one of 1-7.   The copper clad laminated board comprised by laminating | stacking the surface treatment copper foil and resin substrate in any one of Claims 1-8.